Fork Oil: 150 or 180 c.c.'s?

kommando said:

Look at issues with Land Rover air suspension, seals still fail even on Porsche's with air suspension. That plus digressive damping from the advent of shim stacks working better with a constant spring rate has killed off 100% Air springs.

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The "Three Amigos" of system failure lights on P38 RR's comes to mind...

When I had my CRF250R, the forks were fitted with an air bleed from the factory. with regular use it was necessary to bleed the air from the forks daily. Failure to do so increased the stiffness of the ride and reduced the fork seal life.

ando

Stevo said:

Filled mine after new bush and seal refurb with 180cc of 15 weight after seeing the same video. All seems good to me.

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Just realized my error and have corrected the oil viscosity number of the oil I used from 20 to 15.

Tornado said:

AN just dropped a video stating they recommend 180 c.c. fork oil for a Commando vs the workshop guidance of 150 cc per leg...due to notes from racing experience at Thruxton and the 150 c.c. figure is also what the Domi's ran, but they have shorter damper rods than Commando.

FAQ Monday with Ashley - What Oil Should I Use On My Commando Forks?

Ashley is here for another FAQ Monday, answering your question about Norton Commando Forks and which oil should be used in them. This is totally dependent o...

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What is the forum wisdom here?

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Added 30 cc to each fork yesterday, Ran a 120-mile test ride today. Big improvement.

180 c.c. of 20w. Belray Fork oil in each , with new progressive wound springs , seals and new bushes . . . Suspension very good , Enjoy .

kommando said:

Why do you need to google, if air is hissing the forks are not sealed so the air pressure cannot build up enough to have an effect to create a preload, so as adding more oil will not seal the leaks the fork action is unchanged.

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I'm not so sure about this. If air is hissing out, it's taking some time to do so. It probably wouldn't have that amount of time in normal usage. So while not fully airtight, I would think you would still get some level of air-spring effect - ?

Tornado said:

I suppose there are also weight savings with no heavy springs needed. Wonder why no modern bikes have developed no spring forks?

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A friend brought his POS 500cc Honda dual sport asking me to help him rebuild the front forks. I was ignorant of pressurized air in forks so, on disassembly I opened the fork drain screw of the first fork and received a full face/body spray of emulsified water/oil mix. Shit! So on further disassembly I find that there are no fork springs in the fork assemblies. He then told me that he had removed them and just added air pressure to hold them up. He had been riding like that for a while.